1. Field of the Invention
The present invention relates to a tip used for construction or demolition equipment which is adapted to be attached to a support and used in conjunction with, for example, a heavy-duty metal cutting shear, a plate shear, a concrete crusher, a grapple, or other construction or demolition equipment. More particularly, the present invention relates to a replaceable tip secured to a support.
2. Description of Related Art
For purposes of discussion herein, demolition and construction equipment may also be referred to as scrap handling equipment. The description of demolition equipment and construction equipment herein is not intended to be restrictive of the equipment being referenced. Demolition equipment, such as heavy-duty metal cutting shears, grapples, and concrete crushers are mounted on backhoes powered by hydraulic cylinders for a variety of jobs in the demolition field. This equipment provides for the efficient cutting and handling of scrap. For example, in the dismantling of an industrial building, metal scrap, in the form of various diameter pipes, structural I-beams, channels, angles, sheet metal plates, and the like must be efficiently severed and handled by heavy duty metal shears. Such shears can also be utilized for reducing automobiles, truck frames, railroad cars, and the like. The shears must be able to move and cut the metal scrap pieces regardless of the size or shape of the individual scrap pieces and without any significant damage to the shears. In the demolition of an industrial building, concrete crushing devices, such as a concrete pulverizer or concrete crackers, are also used to reduce the structure to manageable components which can be easily handled and removed from the site. Wood shears and plate shears also represent specialized cutting devices useful in particular demolition or debris removal situations depending on the type of scrap. Also, a grapple is often utilized where handling of debris or work pieces is a primary function of the equipment. Historically, all of these pieces of equipment represent distinct tools having significant independent capital cost. Consequently, the demolition industry has tended to develop one type of tool that can be used for as many of these applications as possible.
For illustrative purposes, the following discussion will be directed to metal shears. One type of metal shear is a shear having a fixed blade and a movable blade pivoted thereto. The movable blade is pivoted by a hydraulic cylinder to provide a shearing action between the blades for severing the work pieces. Examples of this type of shears can be found in prior U.S. Pat. Nos. 4,403,431; 4,670,983; 4,897,921; 5,926,958; and 5,940,971 which are assigned to the Assignee of this application and which are herein incorporated in their entirety by reference.
FIG. 1 illustrates a prior art, multiple tool attachment adapted to be attached to demolition or construction equipment, such as a backhoe (not shown). The multiple tool attachment is adapted to connect one of a series of tools or tool units to the demolition equipment. The tool attached in FIG. 1 is a metal shear 10. The shear 10 includes a first blade 12 connected to an upper jaw 13 and a second blade 14 connected to a lower jaw 15, wherein the jaws 13, 15 are pivotally connected at a hub or main pin 16 to a universal body 18. The body 18 is referred to as universal because it remains common to a series of tools or tool units in the attachment system. The universal body 18 is comprised of sides 19, a bearing housing 20, and a yoke 21.
The upper jaw 13 and the lower jaw 15 pivot about the main pin 16 to form a movable jaw assembly 22. At the end of the first blade 12 is a blade tip 24. Details of the blade tip 24 are provided in FIGS. 3 and 4, wherein the blade tip 24 is comprised of a base 26 having a top side 28, bottom side 30, and walls 32, 34 therebetween. The base 26 of the blade tip 24 is a completely solid piece and the top side 28 of the base 26 is secured to a support 36 associated with the upper jaw 13.
Directing attention to FIGS. 1 and 2, the second blade 14 has associated with it a guide channel 38 which accepts and provides lateral support to the blade tip 24 and the first blade 12. To minimize the deflection experienced under load by the first blade 12 and the blade tip 24, the tolerance for the guide channel 38 is fairly low.
In many applications, the first blade 12 and support 36 may be laterally displaced relative to the guide channel 38, such that upon entering the guide channel 38 the side of the blade tip 24 experiences rubbing and extensive wear during normal operation. This wear, if not properly maintained, can lead to the first blade 12 becoming jammed or stuck in the guide channel 38. This condition is known as “stickers” in the industry. Stickers can develop when the clearance gap between the walls 32, 34 of the tip 24 of the first blade 12 and the walls 40, 42 of the guide channel 38 of the lower blade 14 become excessive enough to allow material to become wedged between these surfaces while shearing. Once the first blade 12 becomes stuck within the guide channel 38, the shear 10 must oftentimes be decommissioned for repair. It is then necessary to build up the walls 32, 34 of the tip 24 by welding to keep these gaps at a minimum. This process is very time consuming and costly and, depending on the material that the shear is processing, building up the tip could be required as often as once a week.
FIG. 5 illustrates a prior art design of a blade tip 100 having a base 114 with a recess 132 to accept replaceable inserts 150, 185. Each insert, for example insert 150, has a generally planar top side 152 that mates with the upper side 134 of the recess 132. Additionally, non-circular projections 168 extend from the inserts 150 and fit within matching sockets 166 within the base 114. A common bore 170 extends through the insert 150, the base 114, and an opposing insert 185. A fastener 172 passes through the common bore 170 and secures the inserts 150, 185 within their respective recesses 132, 182. The fastener 172 may be a threaded bolt having a bolt head 174 and a threaded shaft 176 mated with a threaded nut 186.
A tip design is desired that may be easily repaired or replaced when worn to minimize the down time of a shear or other equipment.
Furthermore, a tip design is desired to more uniformly distribute the load generated by cutting forces on the inserts 150, 185 to the base 114.